About the Percentage Calculator
A four-in-one percentage calculator that covers the everyday questions people actually ask: what a percentage of a number is, what percentage one number represents of another, how much something has increased or decreased, and how to add or subtract a percentage from a value.
How to use it
- 01Choose the calculation mode that matches your question.
- 02Enter the two numbers involved (X and Y).
- 03Read the answer and the worked-out formula underneath it.
- 04Switch modes any time; your inputs are reused where sensible.
Features
- Four modes: X% of Y, X is what % of Y, percentage change from X to Y, and add/subtract X% to Y
- Shows the exact formula used so you can verify or learn the math
- Handles negative numbers and decreases automatically
- Instant recalculation as you type, no submit button needed
Practical examples
Tip calculation
What is 18% of a $64.20 bill? Use 'X% of Y' with X=18, Y=64.20 to get the tip amount.
Discount tracking
A $80 item is now $60. Use 'percentage change' from X=80 to Y=60 to see it's a 25% decrease.
Grade calculation
You scored 42 out of 50. Use 'X is what % of Y' with X=42, Y=50 to get 84%.
Limitations
- Division-based modes require a non-zero Y (or X for percentage change) and will show a note if that condition isn't met.
- Results are shown with limited decimal precision for readability; extremely large numbers may lose precision due to floating-point math.
Privacy
All arithmetic runs locally in your browser using JavaScript. Nothing you type is sent anywhere.
Read the full privacy policy for how the site as a whole handles data.
Frequently asked questions
How do I calculate a percentage increase?
Use the 'percentage change from X to Y' mode; a positive result is an increase, a negative result is a decrease.
Can I use negative numbers?
Yes, all modes accept negative numbers and compute correctly, though some real-world interpretations (like percentages of negative totals) may need context.
Why is my percentage-of-total mode not working?
Check that Y is not zero — dividing by zero is undefined and the tool will show a note instead of a result.